This invention relates to lubricating compositions comprising a small amount of an oil-soluble graft copolymer of a methacrylate ester and an ethylene-propylene-alkylidene norbornene terpolymer. More particularly this invention relates to lubricating oils having an improved viscosity index which comprise a lubricating oil base stock having incorporated therein a small amount of an oil-soluble graft copolymer of a methacrylate ester and an ethylene-propylene-alkylidene norbornene terpolymer.